紫胶色素对锦纶纤维的染色热力学研究

为了探讨紫胶色素在锦纶纤维上的染色行为,为染色工艺的优化提供理论参考,进行紫胶上染锦纶纤维的染色平衡实验。用Freundlich、Langmuir和Redlich-Peterson型3种理论吸附模型对80、90℃下的实验数据进行拟合,并计算出染色亲和力、染色热和染色熵等热力学参数。结果表明,紫胶色素在锦纶上的吸附最符合RedlichPeterson型吸附模型,亲和力和吸附量都随着温度的升高而减小,染色热和染色熵分别为-55.45 kJ/mol和-111.96 J/(mol·K),说明染色过程是放热和自发的过程。     

凹凸棒石油脂脱色行为及其机理

以凹凸棒石为大豆油脱色吸附剂,通过对其物理特性、脱色热力学和吸附动力学分析,探讨凹凸棒石吸附剂的吸附行为与脱色机理。结果表明,凹凸棒石吸附剂主要为短晶束和单晶形,其孔径集中分布于1.5～10.0?nm的范围内;脱色热力学分析表明,随着脱色温度升高,凹凸棒石的色素吸附能力逐渐增强,但温度不能改变吸附剂对色素类物质的作用方式;吸附动力学分析表明,叶绿素等微量成分在凹凸棒石上的吸附速率较快,正己烷纯溶液体系中吸附速率依次为叶绿素＞亚油酸＞磷脂＞类胡萝卜素,而大豆油体系中吸附速率依次为叶绿素＞类胡萝卜素＞游离脂肪酸＞磷脂。由此可知,凹凸棒石油脂脱色主要通过孔径填充吸附,并伴随有部分氢键吸附和化学吸附。     

凹凸棒石在大豆油脱色过程中吸附行为的探讨

本论文在475nm下测定了不同吸附剂对油中色素类物质的吸附情况。通过分析所得的热力学参数,比较了活性碳C1和三种具有不同孔径分布的活性凹凸棒石(C2、C3、C4)四种吸附剂对油脂脱色过程中色素类物质的脱除效果。从理论上探索了凹凸棒石这种新型吸附剂在油脂脱色过程中对油中色素类物质的吸附特性。结果表明,活化的凹凸棒石比活性碳具有更强的去除油中色素类物质的能力。同时通过对四种吸附剂的比表面积及孔隙分布数据的分析比较,说明了吸附剂的的比表面积不能决定吸附剂的吸附效果,吸附剂和吸附质的极性越相近,吸附剂的孔径分布和吸附质的截面大小越相似,越有利于吸附作用的发生。     

微孔淀粉对次甲基蓝的吸附热力学与动力学研究

研究了微孔淀粉对次甲基蓝的吸附效果,考察了温度、pH、吸附时间等因素对吸附的影响,以及微孔淀粉吸附次甲基蓝的热力学及动力学特性。结果表明,在30℃、pH为5.0时,吸附1h后吸附率最佳。微孔淀粉的吸附符合Freundich等温方程,焓变ΔHθ=-44.4026kJ/mol,熵变ΔSθ=-0.1239kJ/mol·K,反应吉布斯自由能ΔGθ随温度升高向负方向增加。热力学参数表明吸附过程为放热和自发的。     

沸石改性聚丙烯酰胺复合材料对诱惑红色素的吸附研究

本实验采用一锅法合成了沸石改性聚丙烯酰胺复合材料,并将其作为吸附剂,结合紫外-可见吸收光谱法,研究了其对诱惑红色素的吸附性能。探讨了溶液pH和振荡时间对吸附过程的影响,研究了吸附动力学、吸附等温线和吸附热力学,并对该复合材料进行了再生性能考察。结果表明:在溶液pH为6,诱惑红色素在振荡时间为80 min之内可达到吸附平衡,吸附过程符合拟二级动力学模型(R2=0.9984)和Langmuir等温吸附模型;当温度为20 ℃时,ΔG=(4.23 kJ/mol,ΔH=39.01 kJ/mol,ΔS=145.22 J/mol/K;吸附剂在再生使用3次内吸附性稳定。由此可知,沸石改性聚丙烯酰胺复合材料对吸附诱惑红色素具有良好的吸附性和再生性。     

大孔吸附树脂吸附染料木黄酮的研究

研究了AB-8、S-8两种吸附树脂对染料木黄酮的吸附行为和洗脱条件。结果表明,在298K下,pH=8.0时,S-8吸附树脂对染料木黄酮吸附效果最佳;用乙醇做解析剂,其解析率可达97.50%;其热力学参数为:ΔH=35.9kJ/mol,ΔS=0.128kJ/mol·K,ΔG298K=-2.22kJ/mol。等温吸附过程服从Freundlich方程,表观活化能为33.9kJ/mol。     

大孔吸附树脂吸附染料木素的研究

为了优化染料木素吸附工艺条件,研究了不同pH、洗脱剂浓度和温度等条件下3种大孔吸附树脂吸附染料木素的过程.试验结果表明在pH 4.0时对染料木素的吸附效果最佳;在298K下静态饱和吸附容量为277 mg/g树脂;用乙醇作解析剂,其解析率可达96.5%;其热力学参数为△H=-19.0 kJ/mol、△G=-17.8 kJ/mol、△S=-4.0 J/(mol·K);等温吸附服从Freundlich和Langmuir经验式;表观吸附常数为k298=3.83×10-5/s-1,表观吸附活化能Ea=19.3 kJ/mol.由于XDA-200吸附容量高、洗脱率高,因此适合于染料木素的吸附.     

生物吸附剂壳聚糖对刚果红的吸附

为了确定生物吸附剂壳聚糖对刚果红的吸附行为特征,研究了pH值、初始浓度、时间及温度对刚果红在壳聚糖上吸附的影响。结果表明,pH值是影响壳聚糖吸附刚果红的重要因素,最佳pH值范围为4~7;动力学行为符合Lagergren准二级反应动力学模型,随着温度增加,平衡吸附量减少。吸附过程的表观活化能(Ea)为4.941 kJ/mol。壳聚糖对刚果红的吸附过程较好地符合Freundlich吸附等温方程。计算得到吸附过程的热力学参数△Go和△Ho分别为-10.10 kJ/mol(303 K)和-87.36 kJ/mol,表明壳聚糖对刚果红的吸附是一个自发的放热过程。红外光谱分析可知,壳聚糖吸附刚果红的过程中,壳聚糖分子中存在的大量羟基和氨基发挥了主要作用。     

苯乳酸发酵液脱色体系中活性炭吸附的研究

通过静态吸附实验,研究了活性炭对苯乳酸发酵液脱色体系的吸附特性.将0.5%、1.O%、1.5%、2.0%、2.5%、3.O%的活性炭分别加入到发酵液(pH=4.5～5.O)中,分别在40、60、80、100℃条件下进行等温吸附,采用Langmuir方程和Freundlich方程进行拟合.结果显示,活性炭对苯乳酸发酵液脱色的吸附符合Freundlieh(R2＞0.9597)方程和Langmuir(R2＞0.9656)方程.吸附焓AH为-2.45～6.26kJ/mool,吸附自由能AG为-6.98～-10.69kJ/tool.吸附熵△S为12.6～42.3J/mol·K.活性炭对苯乳酸发酵液中色素的吸附是自发进行的.     

微孔分布对凹凸棒石吸附剂吸附油脂色素的影响

凹凸棒石吸附剂属于多孔固体吸附剂,微孔分布在其吸附过程中发挥了重要作用.对不同来源矿物制备吸附剂样品后发现,凹凸棒石吸附剂存在着跨越一定孔径范围的微孔,胁UrICUich吸附等温线研究结果也表明,不同微孔分布的凹凸棒石吸附剂N值和K值具有明显规律性,但其吸附性质相同.吸附剂的微孔与色素类分子直径越接近,其吸附量会越大,在凹凸棒石对油中色素类物质的吸附的过程中,吸附剂对色素类物质的分子筛分作用不是最重要的.     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the